Nashua, New Hampshire - Magni M24 N327JD - 15th Jan 2020

I regularly fly with pilots in Autogyro gyroplanes whose take-off technique is "pre-rotator off, stick back, brake off, full power" with no reference made to rotor rpm during the initial stage of the take-off roll. Less often, but still too often, I fly with pilots who allow the aircraft to start rolling forwards before the stick is all the way back (btw, if they did that on a test then they would fail). Pilots who use a take-off technique like that are more likely to be caught out when operating a Rotax 915 than they will be with a 912S.

Full power on take-off will not always be the best technique, particularly for a student / low hours / low currency pilot. One has to balance performance requirements against the increased yaw/roll induced by full engine power, particularly when operating at light weight. Taking off on a short strip at MTOW is a very different scenario to solo on a long runway. A 70kg solo pilot flying one of the more popular open-cockpit tandems with a Rotax 914 would rarely have a need to use full power on take-off.

When it comes to training we have to work with the material we have, not what we would like. That often means working with students with no particular talent and at the older end of the age range. Napier Sabres would have been operated by youngsters who had been carefully selected for ability and who would have been thrown off course if they weren't able to meet the required standard. That isn't the world of recreational aviation.
 
How long a delay are you suggesting there is with these guys? As I said it’s a Rotax 915... it’s not that incredible. Good grief. And ignore there is a significant delay then a) training! because b) bringing the stick back isn’t not the recovery.

Monitoring rotor RPMs and not faffing with engine RPM is the way forward.

Why are people passing a test if they are unable to go to full power? I agree that there is a work up but frankly at some point there needs to be some confidence that candidate Blogs is skilled enough to be able to operate the aircraft such that if he goes to airfield 500m he can achieve a safe take off. Otherwise you need to restrict the privileges of the licence.

Who suggested operation of a Napier? I’m just referencing that 140hp doesn’t need some remarkable skill or technique actually- and I say that having flown one AND safely sent a student pilot many times solo flying a 915 sport.
 
I regularly fly with pilots in Autogyro gyroplanes whose take-off technique is "pre-rotator off, stick back, brake off, full power" with no reference made to rotor rpm during the initial stage of the take-off roll. Less often, but still too often, I fly with pilots who allow the aircraft to start rolling forwards before the stick is all the way back (btw, if they did that on a test then they would fail). Pilots who use a take-off technique like that are more likely to be caught out when operating a Rotax 915 than they will be with a 912S.

Timothy,

I fly from an airfield at 7,500 feet in the Colorado Rockies and have a Xenon with the old pre-rotator that can only be engaged with the disk level. I also have the longer blades for my altitude. My Rotax has been modified with the larger 84mm pistons and turbocharger with controllable wastegate so while I have carbs rather than FI, I have about 140hp. I’ve also had the crank welded to handle the extra hp.
I can tell you the technique you describe above for which you would fail a student is the best technique for my machine.
My prerotator only gets me 200 rpm and if I go stick back, release brakes, add power, even if done very rapidly, there is a reduction in rrpm of 40 or more and getting it back is a long process.

if I first release brakes, roll a very short distance and start acceleration, then bring the stick full back, I will lose maybe 10 rrpm and the process to watching for accelerating rrpm, feed more power, balance happens seemlessly and in rapid succession, using less time and runway.

Rob

PS Flying my previous 100 hp Xenon at sea level with short blades and 250 rrpm prerotator; stick back, release brakes, accelerate, always worked fine.
 
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I'm taking flight lessons now and have to comment on your post

"I regularly fly with pilots in Autogyro gyroplanes whose take-off technique is "pre-rotator off, stick back, brake off, full power" with no reference made to rotor rpm during the initial stage of the take-off roll. Less often, but still too often, I fly with pilots who allow the aircraft to start rolling forwards before the stick is all the way back (btw, if they did that on a test then they would fail). Pilots who use a take-off technique like that are more likely to be caught out when operating a Rotax 915 than they will be with a 912S."

My lessons and observations are contrary to your post. Stick forward, prerotate to about 200 RRPM and then release brake and apply additional power, stick back allowing rotor to pick up RPM while also increasing RPM to gain ground speed after rotor has started to cone..

Stick back before RRPM are up begs a tail strike in my opinion and is contrary to my training and Gyropedia info..

Bobby
 
In my experience different gyroplanes have different pre-rotator techniques and different flight instructors may teach it differently.

It is my observation that bringing the rotor back quickly will cause the rotor to slow significantly.

In my opinion sailing a blade because of too much airspeed for the rotor rpm is best avoided.

I find that just teaching the procedure without understanding often leads to a slow relaxing of the procedure and eventually a blade strike.

In my experience most of the gyroplanes I fly can manage full back cyclic and full power at 200 rotor rpm.

Yesterday I flew with a very experienced gyroplane instructor with a very different teaching technique than I use. He flew The Predator as well as I do with no input beyond ground.

We had a conversation with his client and often he would he imagine that he had been taught something different. It was interesting to see that beside our divergent styles we were teaching the same thing.

In the USA when a gyroplane has a mishap the FAA will usually call the flight instructor whose name is in the log book be it a solo endorsement, or training.

Get too many to your name and the flight instructor will usually receive some sort of remedial instruction.

I see pilots flying badly at gyroplane events and it is often because they have not kept their skills up rather than receiving poor training.
 

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In my experience different gyroplanes have different pre-rotator techniques and different flight instructors may teach it differently.

It is my observation that bringing the rotor back quickly will cause the rotor to slow significantly.

In my opinion sailing a blade because of too much airspeed for the rotor rpm is best avoided.

I find that just teaching the procedure without understanding often leads to a slow relaxing of the procedure and eventually a blade strike.

In my experience most of the gyroplanes I fly can manage full back cyclic and full power at 200 rotor rpm.

Yesterday I flew with a very experienced gyroplane instructor with a very different teaching technique than I use. He flew The Predator as well as I do with no input beyond ground.

We had a conversation with his client and often he would he imagine that he had been taught something different. It was interesting to see that beside our divergent styles we were teaching the same thing.

In the USA when a gyroplane has a mishap the FAA will usually call the flight instructor whose name is in the log book be it a solo endorsement, or training.

Get too many to your name and the flight instructor will usually receive some sort of remedial instruction.

I see pilots flying badly at gyroplane events and it is often because they have not kept their skills up rather than receiving poor training.
Vance,

Just curious what specifically were you trying to show with the image below your post.

Rob
 
Nothing in particular Rob, I was landing.
Most of the pictures I have of me flying are from air shows, fifteen with The Predator and two in a Cavalon.
I have flown and trained in most of the gyroplanes out there.
 
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180RRPM before starting takeoff roll and at that point bring stick back gently. That is in a Tango2. Rotor spinup is done with stick forward.
 
I wouldn’t recommend stick fully left or right prior to engaging pre-rotator for wind. Maybe slight adjustment depending on wind strength. All motions with stick should be gently Applied or not abrupt.
 
Good to see monitor rotor RPM is a new addition!

On which basis I wonder why a 915 motor makes a hill of beans difference??

Also Timothy on what basis are students failing a general flight test if they don’t follow either the above or they bring the stick back perhaps a nano second later post brake release? Is this in the UK? If so I don’t think there is any reason.
 
Good to see monitor rotor RPM is a new addition!

On which basis I wonder why a 915 motor makes a hill of beans difference??

Also Timothy on what basis are students failing a general flight test if they don’t follow either the above or they bring the stick back perhaps a nano second later post brake release? Is this in the UK? If so I don’t think there is any reason.


I feel it is reasonable to imagine that more power would allow faster acceleration.

In my opinion blade sailing is about too high an indicated airspeed for the rotor rpm.

In my opinion based on my experience more power does not increase the rate the blades accelerate.

More power may shorten the time between takeoff procedure events.

Phil Harwood’s speculation does not seem unreasonable to me.

Taking a single phrase out of context may not be the best path to understanding.

It may have been in part precipitated by this 915 powered Cavalon mishap in Utah that caused a problem with one of our insurance underwriters. https://app.ntsb.gov/pdfgenerator/R...ID=20190619X22528&AKey=1&RType=Final&IType=CA

The pilot reported that, during takeoff, he rotated around 55 knots and that the gyroplane instantly yawed left about 45°. The pilot reported that he was "behind the power curve" and that the gyroplane could not climb or gain airspeed. The gyroplane began to descend, the pilot turned left, and the gyroplane landed hard and rolled to the right side. The pilot added that he believed that the gyroplane initially yawed left during the climb because of the "P-factor due to [a newly installed] more powerful engine" and that he failed to add right rudder input to correct. He added that it was his first test flight with the new engine. The gyroplane sustained substantial damage to the tailboom. The pilot reported that there were no preaccident mechanical failures or malfunctions with the gyroplane that would have precluded normal operation.

It appears to me from the pilot’s description that his takeoff technique and understanding of the procedures were flawed.

He had flown a 914 powered Cavalon for more than eighty hours so he was not new to the Cavalon.

I have been told this was his first flight in the 915 powered Cavalon although the aircraft had 13.5 hours on the Hobbs at the time of the mishap.
 
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I'm all in favor of Phil's efforts to standardize teaching and build the gyropedia. As it is fairly new I'm sure it will be continually refined for awhile.
The above drawing and text are a good effort but leave some confusion. Some specific to my gyro, other issues more universal.

The original Xenon's did not have a flexible shaft pre-rotator so pre-rotation MUST BE DONE with the disk level so the 90 degree gear box does not shear itself- Prerotation CANNOT be done with the stick fully forward. It seems Gyropedia gives themselves a bit of an out, stating pre-rotation should be done as specified in the manual- however the Gyropedia errors in putting this bullet point AFTER two instructions to pre-rotate with the stick full forward. Perhaps it should read as per the manual OR stick fully forward, etc, so as not to contradict a manufacturers instructions.
I also agree with Dave that the disk/stick should not be placed FULLY into the wind- and again in the Xenon this would result in immediate destruction of the prerotator.

In the Xenon and a number of the dozen or so different gyros I've flown it is easier on the equipment to engage the prerotator at a fairly low engine rpm and increase the engine rpm a bit after the teeth are engaged and as the load of the blades comes on to the engine. So I never use just "an initial power setting" and a "take off power setting" as the gyropedia states.

Rather I have an initial power setting which with a 912/914/915 is going to be around 1800-2000 rpm or wherever idle setting makes your gear box happy. Engage pre-rotator and this usually drops my engine rpm as the load is going to the blades so I increase engine rpm to keep the blades accelerating, then at 200 rpm I release the brakes and begin accelerating and slowly move the stick back - depending on wind, runway gradient etc my engine rpm will be "continually" increasing from its initial 2000 rpm towards it max of 4,000 as my focus is on watching rotor rpm increase to 200. This puts your focus where it should be on making sure engine rpm, airspeed and rotor rpm are all increasing together, after 200 rotor rpm (and increasing) the focus can shift to going to full power smoothly, balancing on the mains and runway alignment with stick and rudder- head outside the cockpit stuff. The only thing that remains is lowering the nose in ground effect until Vy is reached.

I find the instruction to have the stick fully back (or until the nose wheel lifts) quite confusing. This step is BEFORE release the wheel brake. I don't believe I've ever been in a gyro where the nose wheel lifted when I was still stopped and had yet to release the wheel brake.

I've also found that there is usually a specific rotor rpm that is necessary until you can add full power. In the original Xenon manuals part of which I wrote the instruction was not to exceed 4,000 rpm until the rotor was at 200 rotor rpm AND INCREASSING, at which time you could go to full power. The RAF I learned in had a similar instruction to reach a certain rotor rpm before exceeding a specific engine rpm.

Rob
 
The thing is Vance in many ways you can look at things as dancing around the head of a pin because I think it is fair to say most of us instruct (as you highlighted) broadly similar things.

But what is interesting is the little graphic of the take off method has recently changed to now include monitoring rotor RPM - I think that is a good thing but over the last years I've had countless exchanges - including with PH - that have rejected that idea. And this is where the cracks appear. If you are a new / novice / student pilot you happily take all that on board and a year ago nobody using that methodology via the website was using a take off technique monitoring rotor RPMs.. now they are (still a good thing). But at some level that introduces confusion.

I know at least 2 UK examiners that will effect and 1 in particular thinks rotor RPMs are irrelevant.

In fact here is one of your own pilots schooled recently in the same methods but actually no mention of rotor RPMs.


The other problem is now the list is growing - in fact is that the issue with our new Cavalon pilot? You just can't get it all out?

We already know that very many take off snafu are brain fade slips. So piling in more steps to an already long take off process isn't helpful - and we have only just started the ground roll.

That to one side. There is no detail out of context Vance.

I'm just calling out what I feel / see that seems to be nonsense. You now link the Cavalon 915 NTSB report.

Just how can that accident be deemed a blade sail/flap event? It just isn't and wasn't.

If you believe the pilots account he suggests he rotated aggressively and subsequently couldn't climb and felt he was "behind the power curve"... Hmmm what might cause that? Is that blade sailing? I don't think so. He doesn't mention stick shake which is usual as the blades hammer the teeter stops and the description seems to suggest that the time between the initial pitch up and return to earth were long enough for him to be actively doing something to try and remain airborne and he talks of a descent and the pilot actually turns left, the gyroplane rolls right. That doesn't usually happen in blade sail events does it? Indeed its not what the NTSB conclude.

With blade sailing the gyro usually rolls left because of dissymmetry of lift (the retreating blade is physically constrained by the teeter stop) and the speed of the event is over far more quickly that almost no description is really given. See this ex-RAF pilots account of a similar thing in the UK, then the review of the on board video of the same event for detail on how these things occur.


In fact if you take the pilots view of being behind the power curve you might even suggest that not being on full power isn't helpful. Where have I read about full power being an optional extra during take offs???

But the NTSB conclude left yaw. Well here is the result of a 2 min YouTube search and a 914 Cavalon pilot not using enough right pedal (see around 13mins in) lovely production but wandering off to the left. Might seem picky but good grief the aircraft is what? 8ft left of where it starts the take off roll - much further left and its off the side of the runway!


So more accidents with 915 gyroplanes without any check ride / differences training input from the manufacturer? Absolutely I'd agree with that.

More accidents with 915 through blade sail? No I don't agree. Maybe you can peddle a narrative if it suits a particular aim at the time but when you think about a) how these blade sail events happen and b) you monitor rotor RPMs then there is no logic to that view.

Perhaps the former just requires some willingness on the pilots behalf and a few hours with an experienced instructor on 915. The later you can make a mystery, a complex solution and up sell a concept. Perhaps.
 
Agree completely with Brian above- where does "rotating" EVER come in to flying a gyro? If you yank it off the ground before its ready to fly a mushy return to earth is the predicted outcome- and yes it "feels" like being behind the power curve because you are.

Phil the rest of your post is very confusing to me. How can you not pay attention to rotor rpm below 200 rotor rpm AND INCREASING and subsequently why do you need to pay attention to it after you see it at 200 rpm AND INCREASING?

Perhaps what is missing is AND INCREASING.
Perhaps the examiners are unconcerned with rotor rpm after that certain point in the sequence of events.
 
The thing is Vance in many ways you can look at things as dancing around the head of a pin because I think it is fair to say most of us instruct (as you highlighted) broadly similar things.

But what is interesting is the little graphic of the take off method has recently changed to now include monitoring rotor RPM - I think that is a good thing but over the last years I've had countless exchanges - including with PH - that have rejected that idea. And this is where the cracks appear. If you are a new / novice / student pilot you happily take all that on board and a year ago nobody using that methodology via the website was using a take off technique monitoring rotor RPMs.. now they are (still a good thing). But at some level that introduces confusion.

I know at least 2 UK examiners that will effect and 1 in particular thinks rotor RPMs are irrelevant.

In fact here is one of your own pilots schooled recently in the same methods but actually no mention of rotor RPMs.


The other problem is now the list is growing - in fact is that the issue with our new Cavalon pilot? You just can't get it all out?

We already know that very many take off snafu are brain fade slips. So piling in more steps to an already long take off process isn't helpful - and we have only just started the ground roll.

That to one side. There is no detail out of context Vance.

I'm just calling out what I feel / see that seems to be nonsense. You now link the Cavalon 915 NTSB report.

Just how can that accident be deemed a blade sail/flap event? It just isn't and wasn't.

If you believe the pilots account he suggests he rotated aggressively and subsequently couldn't climb and felt he was "behind the power curve"... Hmmm what might cause that? Is that blade sailing? I don't think so. He doesn't mention stick shake which is usual as the blades hammer the teeter stops and the description seems to suggest that the time between the initial pitch up and return to earth were long enough for him to be actively doing something to try and remain airborne and he talks of a descent and the pilot actually turns left, the gyroplane rolls right. That doesn't usually happen in blade sail events does it? Indeed its not what the NTSB conclude.

With blade sailing the gyro usually rolls left because of dissymmetry of lift (the retreating blade is physically constrained by the teeter stop) and the speed of the event is over far more quickly that almost no description is really given. See this ex-RAF pilots account of a similar thing in the UK, then the review of the on board video of the same event for detail on how these things occur.


In fact if you take the pilots view of being behind the power curve you might even suggest that not being on full power isn't helpful. Where have I read about full power being an optional extra during take offs???

But the NTSB conclude left yaw. Well here is the result of a 2 min YouTube search and a 914 Cavalon pilot not using enough right pedal (see around 13mins in) lovely production but wandering off to the left. Might seem picky but good grief the aircraft is what? 8ft left of where it starts the take off roll - much further left and its off the side of the runway!


So more accidents with 915 gyroplanes without any check ride / differences training input from the manufacturer? Absolutely I'd agree with that.

More accidents with 915 through blade sail? No I don't agree. Maybe you can peddle a narrative if it suits a particular aim at the time but when you think about a) how these blade sail events happen and b) you monitor rotor RPMs then there is no logic to that view.

Perhaps the former just requires some willingness on the pilots behalf and a few hours with an experienced instructor on 915. The later you can make a mystery, a complex solution and up sell a concept. Perhaps.

We are not having a debate Phil and I had no idea what you meant when you wrote; “dancing around the head of a pin” so I looked it up and found Noun. angels dancing on the head of a pin pl (plural only) (figuratively) The subject of arcane intellectual speculation; used as an example subject of enquiry the pursuit of which is of no value.

These sounds to me more like your style Phil.

Based on my talks with Phil Harwood I expect the Gyropedia to continue to change. I know he encourages the use of the Pilots Operating Handbook (POH) and in all of the AutoGyro POHs I have seen they emphasize rotor rpm as part of the takeoff procedure.

I suspect as the power increases rotor rpm where it is applied becomes a more important part of the procedure.

What I wrote was that this accident may have precipitated Phil Harwood’s remarks as it impacted his relationship with an underwriter.

I don’t know what caused the accident in Utah although I feel careless application of the throttle may have been a contributing factor. It is not hard to imagine the nose coming up faster with more power.

I don’t see the value in showing a video of a student making a poor takeoff. Most flight instructors I know have seen similar performances and in my opinion it is not indicative of what sort of pilot he will become with further training. Most students I know struggle with pedal work and the concept of cross control.

I feel you may miss the forest for the trees Phil. So you don’t have to look it up the definition is; to not understand or appreciate a larger situation, problem, etc., because one is considering only a few parts of it.
 
"The pilot reported that, during takeoff, he rotated around 55 knots"

Maybe there lies the problem.
Where is this quote from?
From the NTSB preliminary report on N327JD the pilots story is "According to the pilot, he had no recollection of the flight after he received takeoff clearance and he believed that he experienced a medical event during the takeoff. The pilot further stated that he had built the gyroplane in Italy and had flown it fewer than 7 hours, and that everything was working properly prior to the initiation of the flight."
 
Oh the irony.... Brian was refering to the accident you linked to prove a point about blade sailing.

Mind that forest....
 
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